This research project will develop a working in vitro blood-brain barrier model with endothelial cells isolated from human brain microvasculature. This model will allow rapid assessment of the efficacy of drug delivery systems designed to bring pharmaceutically useful compounds to the brain parenchyma. Observed species differences in brain capillary endothelial cells-potential targets for delivery molecules-provides the rationale for developing a model based on human cells. Phase I efforts aim to develop techniques to: isolate human brain capillary endothelial cells from fresh human tissue and 2) establish stable primary cultures of endothelial cells that retain many of their in vivo blood-brain barrier properties. A variety of culture conditions, based on reports of astrocyte-induced specialization by the endothelial cells that form the barrier in vivo, will be examined. Towards the end of Phase I and into Phase II cells will be seeded onto cell culture chamber inserts and the barrier model will be characterized and optimized.